<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        input[type="checkbox"]+label::before {
            content: '\2713';
            /* content: '\a0'; *//* 不换行空格 */
            display: inline-block;
            vertical-align: .1em;
            width: .8em;
            height: .8em;
            margin-right: .2em;
            border-radius: .2em;
            background: salmon;
            text-indent: .15em;
            line-height: .65;
            clip: rect(0, 0, 0, 0);
        }

        input[type="checkbox"]:focus+label::before {
            box-shadow: 0 0 .1em .1em rgb(120, 159, 185);
        }

        input[type="checkbox"]:disabled+label::before {
            background: gray;
            box-shadow: none;
            color: rgb(160, 107, 107);
        }
    </style>
</head>

<body>
    <input type="checkbox" id="awesome" />
    <label for="awesome">Awesome!</label>
</body>

</html>